The invention relates to telecommunications connectors and methods and apparatus for controlling signal delay in telecommunications connectors to improve NEXT, FEXT and return loss in terms of magnitude and upper frequency limits of transmission components and products. Near end crosstalk (NEXT), far end crosstalk (FEXT) and return loss limit tranmission rates of telecommuncations (e.g., voice, data, etc) connectors. Standard compensating techniques involving reactive (e.g., inductive and capacitive) coupling to generate compensating crosstalk to cancel offending crosstalk can only achieve limited success due to the limits defined by the TIA and IEC in terms of the magnitude and phase for both NEXT and FEXT of qualification plugs. ANSI/TIA/EIA-568-B.2-1 defines the magnitude and phase requirements for category 6 test plugs and is shown in the table in FIG. 1.
As an example, the TIA specifies the case 1 plug to have a specified magnitude (36.4 at 100 MHz) and phase −90±1.5*f/100. In order to cancel this offending crosstalk, the telecommuncaitons connector should provide a compensating crosstalk having the same magnitude of NEXT, but opposite phase, +90 degrees, as shown on the graph in FIG. 2. If the phase and magntiude match exaclty, the +90 and −90 lines will cancel each other out. In reality, it is difficult to match this phase exactly.
The failure to match phase of the offending crosstalk and the compensating crosstalk may result in increased NEXT and FEXT. For example, in a telecommunication system using tip and ring transmission pairs, residual current on the tip wire remaining after application of the compensating crosstalk (due to a phase mismatch) may loop back on the ring wire and induce additional compensating crosstalk. Existing solutions now add additional offending crosstalk to couteract the additional compensating crossstalk caused by residual currents. It is desirable to eliminate the need for introducing offending crosstalk.